Pokémon

Only in this Egg Group

Trivia

Pokémon in the Ditto group can breed with any Pokémon from any Egg Group, excluding the Undiscovered Egg Group. However, Ditto cannot breed with members of its own group, meaning that Ditto cannot be hatched from an Egg. The only exception is in Generation II.

Since this group consists of a single Pokémon, it is naturally the Egg Group with the lowest number of types represented, with just one.